The present disclosure relates to a DC-DC converter module in which a switching DC-DC converter is installed in a single package.
DC-DC converter modules each included in a single package are capable of converting power with high efficiency and being mounted in various types of devices because of its small size. Therefore, in recent years, the DC-DC converter modules have been used as a point of load (POL) power supply, which is arranged very close to a load circuit, in various electronic devices such as notebook computers.
FIGS. 4A and 4B show the configuration of a DC-DC converter module disclosed in Japanese Unexamined Patent Publication No. 2004-63676. FIG. 4A is an exploded perspective view and FIG. 4B shows the assembled and finished module. In FIGS. 4A and 4B, a micro converter (a DC-DC converter) 60 is comprised of a module substrate 61, a semiconductor integrated circuit (IC) 62, a micro inductor 70, and stud terminals 80. On the upper surface of the module substrate 61, surface-mounted electrodes and a circuit wiring pattern are formed, for example. On a side end surface of the module substrate 61, surface-mounted electrode terminals (side surface terminals) 63 are formed. The IC 62, the stud terminals 80, and a small number of CR components 64 are mounted on the upper mounting surface of the module substrate 61. The IC 62 includes switching transistors and a control circuit that are integrated therein, and is surface-mounted on the module substrate 61. The micro inductor 70 is a magnetic core inductor configured as a chip component, and mounted to be supported on the stud terminals 80 that are arranged in the four corner portions of the module substrate 61. As can be seen from the foregoing, the micro inductor 70 is placed over the module substrate 61 such that the micro inductor 70 overlaps the IC 62 in the vertical direction, which reduces the mounting area.
Japanese Unexamined Patent Publication No. 2004-63676 does not disclose the inside structure of the micro inductor 70. On the other hand, Japanese Patent Publication No. H10-22137 discloses a typical structure of a thin (planar) inductor of this type.
FIG. 5 is a perspective view showing the inductor disclosed in Japanese Patent Publication No. H10-22137.
In FIG. 5, the inductor 90 has a structure in which a drum-shaped core 91 is provided with a wound wire 92 and an end of the wound wire 92 is wound around an electrode portion 93. As can be understood from this structure, when the inductor 90 is operating, the magnetic flux passes through the drum-shaped core 91, which allows leakage flux to occur above and under the inductor 90.